Reintroduce fix for WebKit audio/video control bug

This fix was first introduced to deal with Chrome < 13 destroying the
appearance of native `audio` and `video` button controls when
`-webkit-appearance` is set on `input[type="button"]`. See #20

Android 4.0.* seems to use a version of WebKit that contains this bug.
See: h5bp/mobile-boilerplate#121

…so the fix needs to be reintroduced.

normalize.scss

@@ -379,19 +379,22 @@ input {
     line-height: normal; // 1
 }
 
-// 1. Improves usability and consistency of cursor style between image-type 'input' and others
+// 1. Avoid the WebKit bug in Android 4.0.* where (2) destroys native `audio`
+//    and `video` controls
 // 2. Corrects inability to style clickable 'input' types in iOS
-// 3. Removes inner spacing in IE7 without affecting normal text inputs
+// 3. Improves usability and consistency of cursor style between image-type
+//    'input' and others
+// 4. Removes inner spacing in IE7 without affecting normal text inputs
 //    Known issue: inner spacing remains in IE6
 
 button,
-input[type="button"], 
+html input[type="button"], // 1
 input[type="reset"], 
 input[type="submit"] {
-    cursor: pointer; // 1
     -webkit-appearance: button; // 2
+    cursor: pointer; // 3
     @if $support-for-ie6-and-ie7 {
-        *overflow: visible;  // 3
+        *overflow: visible;  // 4
     }    
 }